JPS5934164A - Corrugated take-in device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a waveform acquisition device, and particularly to a device for acquiring a signal under test into a storage device such as a digital storage oscilloscope.

Prior Art and Its Problems A digital oscilloscope quantizes samples of an input signal at predetermined time intervals, stores them in a memory, and reproduces and displays the input signal waveform when desired. Until recently, the apparent bandwidth was extremely limited by sampling at sequential sampling clock periods during one period of the input signal due to the asynchronous relationship between the trigger phenomenon and the sampling clock. In the digital oscilloscope field, this mode of operation is called single-shot acquisition.

The apparent bandwidth of this signal acquisition was greatly increased by an acquisition mode similar to random sampling over time. This aspect samples the signal over many cycles of a repetitive signal and reproduces them as a single, equal time cycle signal, even if the waveform samples are taken multiple cycles apart in the input signal. It is something to do.

A problem with such equal time waveform reproduction is that the time required to acquire all of the samples representing each data point can be very long.

Another problem is that there is no correlation between the trigger point, which is the same for each signal cycle, and the sampling clock, which runs at a fixed fixed period, so that the displayed data points may oscillate horizontally relative to each other, or jitter. Sometimes it happens. Regarding this issue, please refer to U.S. Patent No. 4,251,754 (corresponding Japanese patent application: JP-A-56-37) jointly invented by Louis J. Navarroto and Thomas P. D'Agostino and assigned to the applicant of this patent. , No. 564), and here, jitter due to sample instability caused by asynchronization between the sampling clock and the trigger point is corrected by the following method. This method measures the time interval between a trigger recognition event (occurs when the signal level exceeds a predetermined threshold level) and the immediately following sampling clock pulse, and uses that measurement to This system generates an offset current (or voltage) and moves the waveform in the horizontal direction for each frame of display to position each displayed sample at the correct display position. However, since this jitter reduction measure performs correction within the display device, it has the disadvantage that it is difficult to apply to intermediate waveform processing devices such as computers.

Another aspect of equivalent-time waveform reproduction is the effect of the Nyquist lower limit on the sampling period for periodic sampling (
or phenomenon). That is, if the sampling period is less than twice the input signal frequency, information will be lost due to undersampling, and the displayed waveform will be distorted. Therefore, it is desirable to acquire multiple samples for each trigger signal recognition, and to provide the correct equivalent time position to each sample data during the acquisition process.

OBJECTS OF THE INVENTION Accordingly, one of the objects of the present invention is to provide a novel waveform acquisition apparatus and method that is capable of reproducing waveforms over many hours with significantly reduced jitter.

Another object of the present invention is to provide waveform processing that reduces sick by measuring the time difference between a trigger recognition event and its immediately following sampling clock pulse and calculating the correct equivalent time address for each acquired sample block. An object of the present invention is to provide an apparatus and method for embedding.

Another object of the present invention is to provide an apparatus and method that can quickly acquire repetitive signals above the Nyquist frequency of a single phenomenon, yet with the same pre-trigger selection functionality as for single phenomenon signals. .

Still another object of the present invention is to provide a waveform acquisition apparatus and method that can quickly and completely acquire a waveform for many hours using a high-speed analog memory that can hold all the samples acquired at a high sampling rate. The goal is to provide the following.

Other objects of the invention will become apparent to those skilled in the art upon reading the detailed description below, taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION In the waveform acquisition apparatus and method of the present invention, rather than shifting the display horizontally, one or more samples of the input electrical signal are taken and stored at a predetermined memory address for each trigger recognition event. For each multi-sample block, the trigger recognition event and the first instantaneous voltage are sampled at regular intervals determined by the sampling clock generator OFQ. - In a practical example, the sampling clock generator generates sampling clock pulses selectable between 200 KHz and 20 MHz, allowing sampling of analog input signals over a wide frequency range.

The instantaneous values of these analog signals are applied to a high-speed analog memory CO, which is preferably a CCD and is capable of rapidly capturing several samples of the sequentially input signal.

This analog signal is further applied from the preamplifier (14) to a trigger recognition circuit (2), which detects the output of the analog signal as determined by an internal trigger level control, similar to the trigger circuit of a conventional oscilloscope. Further, this recognition gate signal can be generated by an external trigger signal (EXT) applied to this circuit (22) or a commercial power signal (LINE), for example of 60 Hz, as in the case of a conventional oscilloscope. This recognition gate signal is applied to the enable terminal of a preset counter Q4) which can be preset to obtain pre-trigger or post-trigger operation in a conventional manner.The clock input terminal of the preset counter Q4) is , clock pulses are applied.When the final count is reached, a hold signal is applied to the high-speed analog memory (2) to hold the samples stored there.The hold signal from the preset counter 041 is applied to the bus (A). It is also applied to the microprocessor (MPU) system (2) via the microprocessor (MPU) system (2), and informs this MPU, which controls the entire device, that a series of samples have been stored in the high-speed analog memory C!υ. also provides preset information to the preset counter C24) and sampling period information to the sampling clock generator αQ.The actual value is selected by the user of the device using a knob on the front panel or a keyboard (not shown). You can also.

The recognition gate signal generated by the trigger recognition circuit Q is applied to the time interval measuring device C3GK4 to measure the time until the next sampling clock pulse applied from the sampling clock generator α from the trigger recognition event. For example, if a 40MHz high-speed reference clock pulse is
The time interval measurement is performed by applying the voltage from the U system (e) to the time interval measuring device (to).The measured value of 5° is applied in the form of serial data to the MPU system (a) via the bus (a). . As in the past, the MPU system (c) is a read-only system that includes an arithmetic and logic circuit (ALU) for performing logical operations, a random access memory (RAM) for temporarily storing information, and various instructions for a processor. Memory (ROM)
') is allowed.

The MPU system (2) calculates the correct address for the waveform memory C33 based on the time interval measurement information and stores therein the samples contained in the high speed analog memory (a).

The MPU system (to) has a preset counter (24)
When it receives a hold signal from the device and serial data from the time interval measuring device (g), it applies a read clock signal to the high speed memory (a) and the ADCC 34), reads out the stored samples, converts them into digital words, and then converts them to digital words. In the example bus c! 6) to the waveform memo IJC3a and store it at the address calculated previously. This operation is repeated to accumulate each sample at the correct calculated address location to capture the complete equivalent time waveform in waveform memory 02. The waveform imported here is waveform memo IJ 432
The data may be read out at a desired time and displayed on a display system, or otherwise processed.

The display system 06) consists of a conventionally designed digital-to-analog converter (DAC'), an amplifier, and a cathode ray tube for waveform display (
CRT).

FIG. 2 is a simplified waveform diagram for explaining the operation of capturing the repetitive input signal in FIG. 1, and FIG. 3 is a diagram showing the reproduced equivalent time waveform.

In this example, assume that four samples are taken each cycle and that the preset counter Q4) is set to count samples immediately after trigger recognition. As previously explained, the trigger recognition gating signal is generated as soon as the analog signal exceeds the selected trigger level. In the first cycle of the analog input signal, the sampling clock pulse is (la) t (lb) y (lc)
and (1d), and corresponding sampling is performed at these times.

The time interval measuring device 00) measures the time T1 from the front of the trigger recognition gate signal to the first sampling clock pulse (1a). The MPU system CQ receives serial digital data corresponding to the time width T1, and based on this, calculates the address at which four samples should be stored.

Since the sampling interval is constant, once the address of the first sample is determined, the addresses of the following three samples are automatically determined, so there is no need to perform calculations for each sample. If a large number of samples, 32 or more, are obtained per cycle of the analog input signal, this process can prove to be a relatively time consuming task.

In the second cycle of the analog input signal, the sample (
2a), (2b) p (2c) and (2d) are obtained at the corresponding sampling clock pulse instants.

In this case as well, the time T2 between the leading edge of the trigger recognition gate signal and the first sampling clock pulse (2a) is determined. Using this time T2, these four samples (
Find the correct addresses of 2a) to (2d).

The operations described above are similarly repeated for the third cycle, and time T3 is determined to determine the correct addresses for the new four samples. As a result, according to the device of the invention:
Even if a sampling clock pulse asynchronous to the input analog signal is used, each waveform sample is stored in waveform memory 0'.
It can be stored at the correct address in the IJ, and the stored waveform can be read from this waveform memory for further processing or transfer to other equipment as needed.

Figure 3 shows 1 samples of Figure 2 (13-1d, 211-2
d and 33 to 3d) are shown. Of course, in actual waveform acquisition and playback display, more samples are taken to increase the sampling density, so that the input signal waveform is more accurately displayed.

An example time interval measuring device may be any of a variety of known timing devices that measure the time difference between two events. -For example,
This is disclosed in the specification of US Pat. No. 4,301,360 (corresponding Japanese patent application: JP-A-56-66-787) invented by Bruce W. Blair and assigned to the applicant of this patent. In this example, the counter is enabled (energized) only during both phenomena, and high-frequency reference clock pulses are counted during this period. In an embodiment of the invention,
An 8-bit parallel counter is used for this purpose, and a parallel-to-serial converter is used to obtain 8-bit serial data corresponding to the time interval measurements for the MPU system (2EO).

Although it is believed that the characteristics of the present invention have been made clear through the above description, the embodiments shown here are merely examples for implementing the present invention, and do not have any limiting meaning. Therefore, those skilled in the art will understand that the present invention can be modified and modified in various ways depending on the application.

Effects of the Invention As can be understood from the above explanation, the waveform acquisition device of the present invention can utilize an MPU, and similarly to the conventional device, the waveform acquisition device can detect the next sampling clock from the leading edge of the generated trigger recognition gate signal. By calculating the time until the pulse arrives, the correct address of the samples of the input analog signal into the waveform memory is determined for each cycle. As a result, the waveform data stored in the waveform memory is correct regardless of the asynchrony between the trigger recognition gate signal and the sampling clock pulse, so correct waveform data can be reproduced by simply reading out the contents of the waveform memory address by address. Display or other processing is possible. Therefore, the present invention is extremely suitable for digital processing of periodic signals, since it is possible to capture a high frequency input signal as a waveform with reduced jitter, etc. over time.

[Brief explanation of the drawing]

Fig. 1 is a simplified block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the waveform capture operation of Fig. 1, and Fig. 3 shows an example of reproduction and display of an input signal captured by the operation of Fig. 2. It is a diagram. 00)...Input terminal, α6)...Sample/hold circuit, 0 (to)...Sampling clock generator, (2~...Trigger Recognition circuit, T1 to T3... Time between the leading edge of the trigger recognition gate signal and the next sampling clocks, (
3d)...Time measuring device, zero force...memory.

Claims (1)

[Claims] When a periodic analog input signal is sampled at a predetermined period over multiple cycles and then digitally converted and the input signal waveform data is taken into memory, the input signal is compared with a reference level to generate a trigger recognition gate signal. , sampling the input signal at least once during the period of the trigger recognition gate signal, calculating the time between the front line of the trigger recognition gate signal and the next sampling clock pulse, and sequentially collecting the waveform data obtained by the sampling. A waveform acquisition device characterized in that the waveform is stored at a correct address in the memory.